Interlocking system for railroads



A. LANGDON ET AL 2,026,502

INTERLOCKING SYSTEM FOR RAILROADS Filed June 28, 1935 2 Sheets-Sheet 1 Dea. 31, 1935..

Dec. 31, v1935. A. LANGDON ET AL= vINTERLOCKING SYSTEM FOR RAILROADS lFiled June 28, 1955 2 Sheets-Sheet 2 xNvE-NToRs ALANGDON AND aHwloN BY ffm/f m THEmATroRNEY Patented Dec. 31, 1935 PATENT OFFICE INTERLOCKING SYSTEM VFOR RAILROADS Andrew Langdon, Brighton, and George H. Wion, Rochester, N. Y., assignors to General Railway Signal Company, Rochester, N. Y.

Application June 28, 1933, Serial No. 678,042

11 Claims.

This invention relates to interlockingsystems for railroads, and more particularly pertains to the remote control of railroad track switches employed in such systems.

In one type of control system for railroad track switches, the positionsof the levers in the tower are repeated at their respective switch machines so as to control the operating power local. to the track Switches. The positions of the track switches, thus controlled, are then indicated in the tower, or control oflice, by suitably controlling the usual switch position repeating relays over polarized circuits. This general arrangement of control and indication has been employed both where the levers of the interlocking plant have been of the usual four-position mechanically interlocked type, and where the levers have been of the two-position free lever type.

In both cases, one problem has been to insure that the track switches are always in correspondence when not in operation, with their respective control levers and to particularly provide that the control levers can not be juggled out of correspondence with their track switches when the four-position type of mechanical interlocked lever is employed.

The present invention provides for the control and indication o'f track switches in a manner which is so organized and interrelated that the switch position indicating relay for each track switch always indicates the actual position of the track switch, as well as its anticipated operation upon the movement of its control lever to a new governing position. In other words, a system of control wherein the position of the track switch is indicated by the energization of a relay over a polarized circuit has been open to the objection that a new lever movement initiates a switch machine operation prior to the indication of the unlocked condition of the track switch in the tower. However, the present invention eliminates such a condition by positively providing that the switch machine may not operate until an indication of its unlocked condition is given in the tower, or at the point at which power is applied.

Various other features of the present invention reside in the novel circuit arrangements wherein the desired degree of inherent cross protection and safety is provided.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawings in which like reference characters designate corresponding parts throughout the several views and in which:

Fig. 1 illustrates one embodiment of the present invention as applied to a remote control type of installation'having mechanically interlocked switch machine control levers in the tower;

Fig. 1A illustrates a modied form of Fig. 1, 10 wherein free levers may be employed in the tower vby the provision of electric locking.

While certain features of the invention are applicable to, and usable with any type of traic controlling system, the invention has been illus- 15 trated as embodied in the type of remote control'in which the control tower or oice is comparatively local to the track layout, at least sufciently so, as to warrant the use of direct line wire lcontrol as compared to the selector or code type system of control. However, it is to be understood that the present invention may be adapted to a code type system of remote control, all within the scope of the invention as will be more particularly pointed out hereinafter.

With reference to Fig. 1 of the accompanying drawings, a track switch TS is indicated as being operated by a suitable switch machine mechanism SM, which may be of any suitable type, such for example, as disclosed in the pat-y ent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923, but having the control for its. operating motor arranged as provided in accordance with the present invention.

Associated with the track switch TS and the switch machine mechanism SM is a suitable point detector contact mechanism PD which may be oi any suitable type, such for example, as dis- 401 closed in the patent to C. S. Bushnell, Patent No. 1,517,236 dated November 25,1924. For the purpose of simplifying the present disclosure, this point detector contact mechanism has only been illustrated as having movable contacts I0, Il, I2, and I3, but it is to be understood that these contacts are jointly operated by the track switch TS and the lswitch machine SM so as to assume normal or reverse extreme positions when the track switch TS is operated to corresponding extreme positions and locked by its switch machine SM, and to assume intermediate mid-stroke positions whenever the track switch TS is in operation or is unlocked. Y

The switch machine mechanism` includes an operating motor having an armature A and a eld winding F. This motor has its control circuits jointly governed by a control contactor C, a normal contactor NC and a reverse contactor RC. These contactors are in turn controlled by a switch machine lever SML located in the tower as well as being subject to an overload protective device OL. The contactors C, NC, RC and the overload protective device OL are preferably located in a suitable housing within the switch machine mechanism, although some other disposition of the apparatus might be made and still be within the contemplated use of the present invention.

The contactors C, NC, and RC are of the neutral electro-magnetic type and may have their contacts restored to normal deenergized positions by gravity or by some other biasing means. Their structures may be of any suitable design, but their general characteristics are preferably along the lines as disclosed, for example, in the pending application of J. F. Merkel, Ser. No. 552,906, led July 24, 1931, now become U. S. Patent No. 2,002,476, granted May 21, 1935. Those contacts of these contactors which have heavy portions on the movable arm indicate that such contacts preferably have associated therewith suitable magnetic blow-out means to effect the suppression of arcs at such contacts.

The overload device OL is of the usual neutral relay type having contacts which are biased to normally deenergized positions by gravity or other suitable biasing means. This overload device is illustrated as having two windings I4 and I5 which are considered to be upon the same electromagnetic structure although the coils have been shown in spaced positions. The coil I4 is a stick winding; while the coil I5 is the operating winding which carries the operating current of the motor and actuates the contacts of this overload device OL to picked up or energized positions only when the operating current has risen above a predetermined value. Suitable means may be associated with this overload device for delaying its response to surges of current so that it will not trip or operate upon the initial closing of the motor operating circuits. Such means may be retarding short circuiting slugs, or may be special bucking coils, as shown, forexample, in the patent to Hoppe and Swanton, Pat. No. 1,877,876 dated September 20, 1932, all of which is immaterial to an understanding of the features of the present invention although preferable in actual installations.

In the tower or control ofce is located a suitable interlocking machine having a switch control lever SML for governing the operation of the track switch TS. This lever SML operates movable contact members i6, I'I, I8, I9, and 2l) which make contact between their respective pairs of fixed contacts whenin normal or reverse positions respectively. This lever SML operates a tappet bar 2l which extends to the mechanical interlocking panel of the interlocking machine to mechanically interlock the lever SML with the other levers of the system in the usual way. The lever SML has four positions, namely, normal and reverse positions I and 4, and normal and reverse indicating positions 2 and 3 respectively. These positions are determined by the usual indication latch mechanism which has been diagrammatically illustrated as having an indication magnet IM which operates a locking member 22 sliding in a slot 23 in the lever and a lock ing member 24 for engaging the projection 29..on

the lever, all of which is to illustrate the features of a suitable mechanism such as disclosed, for example, in the patent to W. K. Howe, Patent No. 1,846,724, dated February 23, 1932.

Associated with the lever is a suitable locking 5 magnet LM which is controlled in accordance with suitable detector locking, approach locking and the like in accordance with the usual interlocking practices which need not be explained in accordance with the present disclosure for an understanding of the features of the present invention. This lock magnet LM operates a lock bar 30 which engages a projection 35 on the lever in the usual way.

Associated with the indication magnet IM is a magnet relay MR of the neutral slow acting type.

The position of the track switch TS is indicated in the tower by a switch position repeating relay WP which is of the usual polar neutral type.

Power is supplied for the control of the switch machine as well as its operation from a suitable battery source B. This battery supplies power to the interlocking machine over the buses and 26 and to the various switch machines of the interlocking plant over the buses 21 and 28. It 25 is of course to be understood that this battery B might be replaced by any suitable source such as a direct current generator or an alternating current generator, and also that suitable overload protection, terminal blocks and other devices 30 employed in such interlocking plants are also preferably provided in an actual installation although omitted for the sake of simplicity in the present disclosure.

It is believed that the nature of the invention, its advantages and characteristic features can be best understood with further description being set forth from the standpoint of operation.

Operation Under normal conditions, the switch machine control lever SML is in a full normal position I in correspondence with the normal position of the track switch TS. With such normal conditions established, the point detector contact mechanism has its movable contacts Ill, Il, I2 and I3 in normal extreme positions with the track switch TS in a normal position and locked by the switch machine SM.

This completes a normal energizing circuit for the relay WP from the positive bus 2l, through bus wire 3l, wires 40 and 4I, back contact 42 of contactor C, wires 43 and 44, movable contact I2 of point detector contact mechanism PD in a normal position, wire 29, windings of re- 5 lay WP, wire 3l), movable contact I3 of point detector contact mechanism PD in a normal position, wires 4B, lil, and 43, back contact 49 of reverse contactor RC, wire 5D, back Contact 5I of normal contactor NC, wire 52, bus wire 32, to the negative bus 2B. The energy, which flows in this normal energizing circuit for the relay WP, causes its neutral contacts to be actuated to energized positions and its polar contacts to be actuated to right hand normal positions. Under such circumstances, the signal control circuits which can be properly completed with the track switch TS in a normal position may be closed, if desired, as the movable contact 20 of the lever SML is in 70 a normal position in correspondence with the polar contact 53 of relay WP and the neutral Contact 54 of relay WP is picked up.

Normal to reverse operation-Let us assume that the operator desires to operate the track 75 switch TS from its normal locked position to its reverse locked position. To do this, he actuates a lever latch (not shown) which closes a contact (not shown) allowing the lock magnet LM to be energized providing the approach locking and `detector locking is in condition to allow safe operation of the track switch. The energization of the lock magnet LM causes the locking member 39 to be picked up so that the lever SML'may be freely moved to the reverse indicating position 3.

The indication magnet IM is deenergized allowing the locking member 22 of the indication latch mechanism to freely drop into the lower portion of the slot 23, and the locking member 24 remains in a lowered position to avoid the detent 29.

However, the reverse movement of the lever SML is stopped at position 3 by reason of the locking member 22 of the indication latch mechanism.

Also, the tappet har 2| is operated to a mid stroke position in which the conicting levers are prevented from operation by mechanical locking.

With the lever SML in the position 3, the signal control circuits are broken as the movable contact member 29 is out of correspondence with the polar 4contact 53 of the relay WP.

With the movable contact member I6 in the position 3, the reverse contactor relay RC at the track switch location is energized by a circuit closed from the positive bus 21, through bus wire 9|, wire 55, back contact 56 of contactor C, wires 51 and 58, movable contact |9 of point detector contact mechanism PD in a normal position, wire 59, windings of reverse contactor RC, wire 69, back contact 6I of normal contactor NC, wire 62, back contact 63 of overload device OL, line wire 33, jumper wire 64, contacts 65-I6, wire 66, to the negative bus wire 26.

The response of the reverse contactor RC opens the normal energizing circuit for the relayrWP at its back contact 49 and closes a shunt circuit for the relay WP at its front contact 49. This shunt circuit for the relay WP is closed from its right hand terminal, through line wire 39, movable contact I3 of point detector contact mechanism PD in a. normal position, wires 46, 41, and 46, front contact 49 of reverse contactor RC, wire 44, movable contact |2 of point detector contact mechanism PD in a normal position, line wire 29 to the left hand terminal of the relay WP. v

This opening of the normal energizing circuit of the relay WP and the shunting of its windings causes its neutral contacts toy drop away, thereby indicating the equivalent of the unlocked condition of the track switch TS although up to this time no operation thereof has occurred.

The deenergization of the relay WP and the closure of its back Contact 69 allows energizing current to be applied to the contactor C which then completes the operating circuit of the switch machine motor including the armature and eld windings A and F.

This reverse energizing circuit for the contactor C is closed from the positive bus wire 25, wire 68, back contact 69 ofrelay WP, wire 19,

contacts 1I--I1, jumper wire 12, line wire 34,v

back contact 'E3 of overload device OL, wire 14, front contact 15 of reverse contactor RC, wires 16 and 11, windings of contactor C, wire 18, bus wire 32, to the negative bus 28.

This energization of the contactor C completes the reverse operating circuit for the switch machine motor from the positive bus 21, through bus wire 3|, wires 80 and 8|, front contact 82 of reverse contactor RC, Wire 83, field windings F, wire 84, overload coil I5 of the overload device OL, wire 85, back contact 86 of normal contactor NC, wire 81, front contact 88 of contactor C, armature winding A, wire 89, bus wire 32, to the negative bus 28. This energization of the armature and eld' windings A and F causes the unlocking of the track switch TS and its operation to a reverse extreme locked position.

It is to be noted that this picking up of the contactor C connects the reverse contactor RC across the control line wires 33 and 34, as the iront contact 56 of the contactor C is now closed. This circuit is closed from wire 34, through the back contact 13 of overload device OL, wires 14 and 90, front Contact 9| of reverse contactor RC, wires 92 and 93, front Contact 56 of contactor C, wires 51 and 58, movable contact I9 of point detector contact mechanism PD in normal and mid stroke positions, wire 59, winding of reverse contactor RC, wire 60, back contact 6| of normal contactor NC, wire 62, back contact 63 of overload device OL to wire 33. This means that the reverse contactor RC is now subject to energize.- tion through its stick circuit including its own front contact 9| and the line wires 33 and 34. It should be noted that contact 56 is preferably a make-before-b-reak contact so that the reverse contactor RC will not be momentarily deenergized upon the shift of this contact to a picked up position. 1

As soon as the contactor C is picked up, the circuit for relay WP is further opened at back contact 42 and a second shunting circuit is completed for the relay WP from its right hand terminal through line wire 30, movable contact I3 of point detector contact mechanism PD in a normal position, wires 46 and 41, front contact 42 of contactor C, wires 43 and 44, movable contact I2 of point detector contact mechanism PD in a normal position, line wire 29, to the left hand terminal of relay WP.

Also, at the time the track switch TS is unlocked, the contacts I9, II, I2, and I3 of the point detector contact mechanism PD are moved to mid-stroke positions. the contactor. NC or RC is not broken by such movement, as the contacts I 9 and II maintain their respective circuits closed in moving in the proper direction toward their mid-stroke positions, in such a manner that both their respective circuits are closed in the mid stroke position. This is diagrammatically illustrated by the jumpers 94 and 95. With the movable contacts I2 and I3 in mid stroke positions, ashunt circuit is completed for the relay WP by connecting the wires 29 and 30 through the jumper I 39.

Assuming that the proper operation of the track switch TS takes place, then at the end of the operating stroke, when the switch machine SM has locked the track switch TS in an extreme reverse position, the movable contacts I9, il, i2, and I3 of the point detector contact mechanism PD are operated from mid stroke to extreme reverse positions. Although the movable contacts I2 and I3 are in reverse positions, the relay WP thereby being unshunted insofar as the jumper I 39 is concerned, another shunt circuit is completed until the contactor C assumes a deenergized position. This shunt circuit is closed from the wire 29, through movable contact i2 in a reverse position, wires 96 and 46, front contact 91 of contactor C, wires 98 and 99, movable contact I3 of point detector contact mechanism PD in a reverse position, to the wire 30.

45 The energizing circuit for tact e2,

Upon the movement oi the contact Ii! of the point detector contact mechanism PD to a reverse position, the stick circuit for the reverse contacter RC is opened and its contacts drop away and thereby deenergize the contacter C by opening its circuit at front contact 15.

It is to be noted, that the deenergization of the contacter RC initially opens the energizing circuit o the switch machine motor at iront conand thon shunts the field winding F from its lower terminal through wire 83, back con tact 82 of contacter RC, wire IUI, back contact 86 of contacter NC, wire 85, overload winding I5, wire 84, to the upper terminal of the eld winding F. The deenergization of the contacter C shunts the armature A by the closure of its back contact 83 through an obvious circuit. The short circuiting of beth the field and armature windings accomplishes an appreciable dynamic snubbing effect for the switch machine mechanism te bring it quickly to rest.

As soon as the contacters RC and C are both deenergized, then the reverse energizing circuit is closed for the switch position indicating relay WP irom the positive bus 21, through bus wire 3|, wires 49 and |32, back contact 91 of contacter C, wires S8 and 99, movable contact I3 of peint detector contact mechanism PD in a reverse position, wire 36, windings of relay WP, wire 25, movable contact I2 of point detector contact mechanism PD in a reverse position, wires 96, 46, 41, and 48, back contact 49 of contacter RC, wire 53, back Contact 5I of contacter NC, wire 52, bus wire 32, to the negative bus 28. This causes the polar contacts of the relay WP te be actuated te left hand reverse positions and the neutral contacts of the relay WP to be actuated to picked up positions.

It is to be remembered that the lever SML was assumed to be operated from its normal position I to the reverse indicating position 3 from which it is te be operated to the full reverse position 4 upon the reception of an indication of the cornplete reverse operation of the track switch TS. Returning for a moment to the initial operation of the lever to the position 3, an energizing circuit is closed for the magnet relay MR with the lever cut of correspondence with the position of the track switch as indicated by the relay WP.

This reverse out of correspondence energizing circuit for magnet relay MR is closed from the positive bus 21 through bus wire 25, wire |03, front contact It@ of relay WP, wire |65, polar contact |66 of relay WP in a right hand position, wires |61 and |33, contacts II9-I9, wires II) and III, windings of magnet relay MR, wire II2, bus wire 26, to the negative bus 28. This circuit is closed only so long as the relay WP remains energized and is more particularly useful for the purpose of restoring the lever to its full former position in the event that there fails to be a response in the control system sufficient to deenergize the relay WP which will be described in detail under the heading If system fails to respond.

Under the normal operation of the system as assumed in the present case, the relay WP becomes de-energized upon the response of the contacter RC to the control lever and the closure of its back contact |64, thus effected, completes an energizing circuit for the magnet relay MR from the positive bus wire 25, wire |63, back contact |54 of relay WP, wires II3 and III, windings of relay MR, wire I I2 to negative bus wire 26. Thus,

the magnet relay MR is energized throughout the operation of the track switch TS.

Then, at the completion of the operation of the track switch TS, and upon the energization of the relay WP which actuates its pelar contacts 5 to the left and its neutral contacts to picked up positions, the magnet relay MR is cle-energized by the opening of back contact IIJ4 so that after a predetermined time its contacts drop away, but before this predetermined time elapses, the 10 indication magnet IM is momentarily energized by a circuit closed from the positive bus 25, wire |03, front contact |64, wire |65, polar contact |66 of relay WP in a left hand position, wire I I4, contacts IIS-I8, wire IIS, windings of indica- 15 tion magnet IM, wire II1, front contact II8 of magnet relay MR, wire II9, to the negative bus 26. This momentary energization of the indication magnet IMVactuates its locking member 22 to an unlocked position, so that the opera- 20 tor may operate the lever SML to a full reverse position 4, in correspondence with the position of the track switch TS.

Reverse to 'normal operation-It is readily apparent that the operation of the track switch 25 TS from a reverse position to a normal position is merely an inverse function ef the operation pointed out above, and therefore need not be explained in detail. However, it is considered expedient te point out the different circuits in- 30 volved although the associated operation is not fully explained in connection therewith.

With the lever SML in the normal indicating position 2 and the track switch TS in a reverse position, the initial energizing circuit for the 35 normal contacter NC is closed from the positive bus 21, through bus wire 3|, wire 55, back contact 56 of contacter C, wires 51 and |29, movable contact II of point detector mechanism PD in a reverse position, wire |26, windings of normal 40 contacter NC, wire I2I, back contact 15 of reverse contacter RC, wire 14, back contact 13 of overload device OL, line wire 34, contacts i22-I 1, wires |23 and 65, to the negative bus 26.

The normal pick-up circuit for the contacter C 45 is closed from the positive bus wire 25, wire 68, back contact 69 of relay WP, wires 10 and I 24, contacts i25--I6, line wire 33, back contact 63 of overload device OL, wire 62, front contact 6I of contacter NC, wire 11, windings of contacter 50 C, wire 18, bus wire 32, to the negative bus 28.

The normal stick circuit for the normal contacter NC is closed from the positive bus wire 25, wire 68, back contact 69 of relay WP, wires 10 and |24, contacts |25-I6, line wire 33, back 55 contact 63 of overload device OL, wires 62 and |26, front contact |21 of contacter NC, wires |28 and 93, front contact 56 of contacter C, wires 51 and |29, movable contact II of point detector contact mechanism PD in reverse and mid-stroke 60 positions, wire |26, windings of normal contacter NC, wire I2 I, back contact 15 of reverse .contacter RC, wire 14, back contact 13 of overload device OL, line wire 34, contacts I22-I1, wires |23 and 66, to the negative bus 26. When the point de- 65 tector contact mechanism PD operates movable contact II to a mid-stroke position, the jumper wire is considered as the equivalent of a sliding contact so that the normal stick circuit for the normal contacter NC is continued intact through- 70 out the normal operation of the track switch TS.

The normal energizing circuit for the switch machine motor is closed from the positive bus 21, through bus wire 3|, wire S5), front contact 86 of normal contacter NC, wire 85. overload 75 winding I of overload device OL, Wire 84, eld winding F, wire 83, back contact 82 of reverse contactor RC, wires IGI and 81, iront contact 88 of contactor C, armature winding A, wire 89, bus wire 32, to the negative bus 28.

With the normal contactor NC picked up and the contacts of the contactor C still de-energized,

before the response of the movable contacts I2 and I3 of the point detector contact mechanism PD, the circuit for relay WP is broken at back contact 5I anda shunt circuit is closed for the relay WP from Wire 29, through movable contact I2 of point detector contact mechanism PD in a reverse position, wires 96, 46, 41, and 478, back contact 49 of reverse contactor RC, wire 5|), front contact 5I of normal contactor NC, wire 99, movable contact I3 of point detector contact mechanism PD in a reverse position, to the wire 30.

With both the contactors NC and C picked up, a shunt circuit is closed from the wire 29 through contact I2 of point detector contact mechanism PD in areverse position, wires 9S and 46, front contact 91 of contactor C, wires 98 and 99, movable contact |3vof point detector contact mechanism PD in a reverse position to the wire 30.

, During the operation of the track switch TS While it is unlocked, the movable contacts I2 and |`3 are in mid-stroke positions so that the wires 29 and 3S are shunted by the jumper wire |36.

At the end of the normal operation, with the contactors NC and C energized but with the movable contacts I2 and I3 in normal positions a shunt circuit is closed from wire 29 through the movable contact I2 of point detector contact mechanism PD in a normal position, wires 44 and 43. front contact 42 of contactor C, wires 41 and 46, movable contact I3 of `point detector Contact mechanism PD in a normal position, to wire 30. Thus the shunt circuit is maintained closed until the normal energizing circuit for the relay WP (above described) is completed upon the dropping away of the contacts of the contactor C. In other words, the contactor C is always the last to becomefpicked up at the beginning of a cycle of operation and is always the last to be dropped at the end of a cycle of operation.

The normal out of correspondence energizing circuit for the magnet relay MR is closed from the positive bus wire 25, wire |93, front contact |34 of relay WP, wire I 65, polar contact I 66 of relay WP in a left hand position, wires II4 and I3I, contacts |32-I9, wires |33, III) and III, windings of magnet relay MR, wire II2, to the negative bus 26. n

The normal energizing circuit for the indication magnet IM at the completion of the normal operation is closed from the positive bus 25, wire |93, front contact |94 of relay WP, wire |05, polar contact |96 of relay WP in a right hand position, wire 81, contacts ISL-I8, wires |35 and IIE, windings of indication magnet IM, wire I I 1, front ycontact H8 of magnet relay MR, wire I I9, to

the negative bus 26.

Reversal in mid stroke-When the track switch TS is in operation, the movable contacts I6 and |I oi' the point detector contact mechanism PD are in midstroke positions, so that either one of the contactors NC or RC may be picked up to cause the opposite operation of the switch machine. l-Iowever, these contactors are interlocked in such a manner that each is picked up through a back contact of the other so that only one may be picked up at any one time. If a particular contactor is picked up and energized through its stick circuit which is completed during operation of the track switch, and the lever SML is moved to an opposite governing position,

the direction of current ilow in the windings of this contactor is reversed so that the magnetic iiux in its winding is reduced to substantially zero and its contacts are dropped away. As soon as the contacts of that contactor drop away, the opposite contactor may be energized in accordance with the new position of the lever SML.

For example, assuming that the reverse contactor RC is maintained energized through its stick circuit during the reverse operation of the track switch TS, it is apparent that the current is flowing from left to right in its windings; but if the lever SML is moved to a normal governing position 2, then the direction of current flow in the windings of the contactor RC is reversed so that its contacts drop away. This allows the normal contactor NC to be energized through back contact 15.

During such a reversing operation, the contactor C will drop away due to its circuit being opened by front contact 6| or 15, and it must drop away before the opposite one of the contactors NC or RC can be picked up as their pickup circuits include back contact 56.

While the track switch 'TS is in operation, the relay WP is de-energized for reasons above pointed out so that irrespective of they movement of the lever SML from one governing position to the other, the magnet relayrMR is energized by reason of back contact |04 so that upon the completion of the operation of the switch into correspondence with the lever, the indication magnet IM is energized allowing the nal movement of the lever to unlock the mechanical locking,

Operation in the event of overload-It is apparent that the overload Winding I5 of the overload device OL is included in series with the iield winding F of the seriesmotor circuit, `so that in the event of an occurrence of an overload thereby causing an abnormal current iiow above a predetermined value, the contacts 63 and 13 of the overload device OL are operated to picked up positions. When the front contact 63 of the overload device OL is closed, the stick winding I4 is connected across the wires 33 and 34 thus energizing the winding I4 with a polarity depending upon the position of the lever SML. yThis polarity of energization is in correspondence with the polarity of energization as produced in the overload winding I5 for that operation, so that the contacts 63 and 13 are maintained in picked up positions. The contact 63 is preferably of the make-before-break type, so as to insure that its contacts are picked up once the overload coil I5 has been eiective to initially cause its actuation.

The stick winding I4 is maintained energized until the lever SML is operated to an opposite position, at which time the energization of its winding in the opposite direction reduces the magnetic flux in the overload device OL to substantially zero so that its contacts drop away breaking its stick circuit at front contact 63 so that its contacts remain in dropped away positions. Thus, during an operation if the overload device OL is operated, its contacts remain operated until the lever SML is moved to the new position. It is readily apparent that the operation of the contacts 63 and 13 to picked up positions opens the pick-up and stick circuits for the contactors NC or RC s0 that they drop and open the motor circuit.

In the event that it is desired to provide some means associated with the overload winding l5 to prevent a temporary surge from operating the overload device OL as distinguished from a regular overload, suitable means as disclosed in the patent to Hoppe et al., Patent No. 1,877,876 dated September 2G, 1932, may be employed.

I f the system fails to responda- The system of the present invention provides that the lever SML may be returned to a full normal or reverse position from which it has lbeen operated to the opposite half operating position providing there has been no response to unlock the track switch TS.

For example, if the operator moves the lever SML from a full normal position i to the reverse indicating position 3, and for some reason, such as a broken line wire 33 or 34, the switch TS fails to respond and the relay WP remains energized, the operator may return the lever SML to the normal indicating position 2 and receive an energization of the indication magnet IM to return the lever to the full normal position I.

This may be accomplished because the magnet relay MR is energized by an out of correspondence circuit, previously described, with the lever SML in the position 3. Thus, upon the return of the lever SML to the position 2, the relay MR is picked up so that an energizing circuit for the indication magnet IM is immediately closed. The relay MR is suiciently slow acting to allow such operation, which is of course possible both for normal and reverse movements of the lever.

This return of the lever under such conditions has heretofore been unknown as there has been no way of distinguishing between a situation where the relay WP remained energized in spite of lever operation or where the relay WP became energized at the end of a lever operation. In the present system, the de-energization of the relay WP not only indicates the operation of the track switch TS but the anticipated operation of the track switch so that at any time that the relay WP is energized it is perfectly safe to release the lever to operate it to a full position in correspondence with the direction of energization of the WP relay. These features may perhaps be best understood by considering the various conditions under which levers of the fourposition type may possibly be juggled out of correspondence with their track switches which they control.

Lever iuggZz'ng.-Heretofore there have been two points in the cycle of operation of a track switch employing the so called battery or constant current type of indication at which the lever could be juggled out of correspondence with its track switch. These two positions have been at the beginning and the end of the cycle of operation.

At the beginning of a cycle of operation of a track switch, the diiculty arose that the lever could be moved to a new governing position giving the switch machine a temporary application of energy and immediately returning the lever to the former governing position before its indicating relay WP would become fie-energized, and thereupon receiving an energization of its indication magnct to return the lever to a full former position. The lever thus returned to a full former position, would unlock the associated mechanical interlocking and allow signals to be cleared although the switch machine may have, upon the temporary application of power, unlocked the track switch and failed to return to a corresponding full former position upon the return of the lever SML to the full former position.

The present invention obviates such a condition by providing that the indication relay WP shall be de-energized before power shall be applied to the track switch operating mechanism. Thus, if the lever is moved to a new governing position and returned prior to the de-energization of the relay WP, it is perfectly safe to actuate the indication magnet as there has been no application of power to the switch machine. If the relay WP has been cie-energized at the beginning of the operation and has applied power to operate the switch machine and the lever is returned to its former governing position, all of the contact mechanisms at .the switch machine and the point detector contact mechanism must be in correspondence with the new governing position of the lever, with the motor de-energized, in order to again energize the relay WP in correspondence with the lever to thereby receive an indication. In other words, it is impossible with a system provided in accordance with the present invention to operate the lever' out of correspondence with the track switch at the beginning oi' the operating stroke.

At the end o a cycle of operation of a track switch, the difficulty arose that a lever, instead of being left in its new governing position allowing the switch to fully complete its operation, could be moved to its former position momentarily just prior to the locking up of the switch in the new position and then returned to the new governing position to receive an indication because the switch would have continued to operate to lock up momentarily and then be operated in the opposite direction toward its former position. If it happened that, due to the lever manipulation just cited, the switch became momentarily energized to operate toward its former position just enough to unlock the track switch and then failed to follow the change of the lever position to its new governing position, this would then leave the lever in the full position corresponding to its new governing position with the track switch unlocked.

This sequence of events is not applicable to the system of the present invention, as a definite sequence of events in the operation of the track switch is in force wherein the indicating relay WP is caused to anticipate, so to speak, the operation of the track switch so that it is always deenergized before the switch machine actually receives power.

In former types of systems where the indicating relay WP merely repeated the position of the track switch, it is apparent that the track switch would necessarily be unlocked and operated before such an indication could be given, and with this former type of arrangement the undesired possibility of the failure of the switch to follow at the end of an operating cycle when the lever was quickly juggled was quite possible, but the present system eliminates this possibility.

Thus, the present system provides, a sequence of events in the control and indication of a track switch for the four-position type of interlocking lever wherein the full position of the lever cannot be attained unless the track switch is deenergized and in a corresponding extreme locked position.

M odiyed forca- In Fig. 1A, is disclosed a form of the present invention employing the so called free lever embodied in the lever CL. Associated with this lever CL is a repeating relay WZ of the polar-neutral type. The lever contacts |50 and |5| operated by the lever CL apply potential to the relay WZ in one direction or the other to cause the relay WZ to repeat the lever positions and control the application of power to the switch machine by governing the line wires 33 and 34 in a similar manner as the lever contacts of the lever SML in Fig. 1. A lock relay L which is controlled in accordance with suitable approach and detector locking interrupts the control of the lever CL over the relay WZ so as to prevent further operation of the track switch under certain unsafe traino conditions. In such cases, any control of the switch machine SM already initiated upon such interruption, is completed in spite of any lever movements to the contrary.

The switch position repeating relay WP is controlled in the same manner, as heretofore described, but the correspondence between the relay WP and the relay WZ is indicated by normal and reverse relaysl N and R which are interlocked through each other and which are suitably selected.

Although the illustration of Fig. 1A shows the lock relay L, the control relay WZ, the indicating relay WP and the signal circuit selecting relays N and R as located in the control tower, it is to be understood that any suitable disposition of the apparatus may be made, and these devices and circuits may be located in the field if the wires |52 and |53 are made the line wires in place of the wires 33 and 34 for connecting the control tower and the field location. Irrespective of the particular disposition of the apparatus, the operation remains the same in each case.

More specifically, the control lever CL when in the normal position illustrated energizes the control relay WZ through a circuit from the positive bus 25, wire |51, lever contact |5| in a normal position, wire |53, front contact`|55 of lock relay L, wire |B|, windings of relay WZ, wire |60, front Contact i 54 of lock relay L, wire |52, lever contact |56 in a normal position, wire |56, to the negative bus 26. Current flowing in this normal energizing circuit actuates the polar contacts of the relay WZ to right hand positions and its neutral contacts to picked up positions.

When the lever CL is operated to a reverse position, the direction of current flo-w in the relay WZ is reversed by reason of a circuit .closed from the positive bus 25, through wires |51 and |59, control lever contact |56 in a reverse position, Wire |52, front Contact |54 of lock relay L, wire |66, windings of relay WZ, wire IBI, front contact |55 of lock relay L, wire |53, control lever contact l5! in a reverse position, wire |58, to the negative bus 26. The current which flows in this energizing circuit actuates ther polar contacts of the relay WZ to lefthand positions and itsneutral contacts to picked up positions.

The lock relay L is normally energized, so that the movement of the control lever CL is repeated by the relay WZ. The operation ofthe relay WZ to a new position controls the corresponding apparatus at the eld station over the line wires 33 and 34 as explained in connection with Fig. l. In other words, the polar contacts |62 and |63 serve the same purpose as the contacts 65, |25, 1|, |22, I6 and |`l' of Fig. 1 insofar as the reversal of polarity upon the line wires 33 and 34 is concerned. The back contact |64 of relay WP serves the same purpose as the back contact 69 of Fig. 1. Thus, it can be seen that the polar contact |63 of relay WZ serves to control the initial energization of the contactors RC and NC; while the polar contact |62 is effective to control the energization of the contactor C following the deenergization of the relay WP and the closure of back contact |64 in response to the initial energization of the normal or reverse contactor NC or RC.

This arrangement provides that the same sequence of events occurs when the apparatus of Fig. 1A is employed in the tower as when the apparatus in Fig. 1 is employed in the tower.

When the track switch TS is in a normal position and locked as repeated by the relay WP, and the switch control relay WZ is in correspondence with the position of the track switch, a normal relay N is energized by reason of the circuit closed from the positive bus 21, through wires |55 and |66, front contact |61 of relay WP, wire |68, polar contact |69 of relay WP in a right hand position, wire |16, windings oi relay N, wire back contact |12 of relay R, wire |13, polar contact |14 oi relay WZ in a right hand position, wire |15, front contact |15 of relay WZ, wires |11 and |18V to the I negative bus 28.

On the other hand, with the track switch TS in a reverse position and locked as repeated by the relay WP in correspondence with the relay WZ in a reverse position, the reverse relay R is closed by reason of a circuit from the positive bus 21, wires |65 and |66, front contact |61 of relay WP, wire |63, polar Contact |69 of relay WP in a left hand position, wire |80, back contact |8| of relay N, wire |82, windings of relay R, wire |83, polar contact |14 of relay WZ in a left hand position. wire |15, front contact |15 of relay WZ, Wires |11 and |18, to the negative bus 28.

The energization of the normal relay N permits the signal control circuits to be selected in accordance with the normal position of the track switch TS; while the energization of the reverse relay R permits the signal control circuits to be selected in accordance with the reverse position of the track switch. Only one of these relays N and R can be energized at a time because of the selection of each through a back contact of the other.

The signal control circuits are illustrated as including front contacts |34 of relay N, iront contact of relay R and back Contact |86 of relay L. The signals cannot be cleared until the back contact |86 of relay L is closed, which occurs upon the actuation of the signal control lever to a clearv ing position. In other words, the initial actuation of the signal control lever (not shown) causes the locking up of the track switches included in the route to be cleared, and after such locking has occurred the signals may be cleared in accordance with the route selected, Such a control for the lock relays has been illustrated in the pending application of Larry et al., Ser. No. 577,504, filed. November 27, 1931. It is of course to be understood that any other suitable control may be employed in connection therewith such as shown for example, in 'the pending application of Dicke et al., Ser. No. 640,318 filed October 31, 1932.

Whenever the lock relay L is deenergized, the

Y relay WZ is maintained in its last actuated position by reason oi stick circuits including back contacts |54 vand |55 of lock relay L and polar in an energized position has been illustrated, it is Y contacts |81 and |68 of relay WZ. It is obvious4 to be understood that the polar contacts of the relay WZ are preferably of the stay-where-put type irrespective of the energization of the relay. Summary- The above description points out ie manner in which the interrelation between a switch indicating relay WP and the control of the switch is accomplished in such a manner that a predetermined sequence of events is required to thereby prevent the juggling of the control lever out of correspondence with the switch which it controls irrespective of the quick manipulations which may be accomplished. This type of system in accordance with the present invention has been illustrated as adaptable both when the mechanical type of interlocking and the electrical type of interlocking with free levers are employed. In the later mentioned type of interlocking, it is of course understood that the control lever may be operated to an out-of-correspondence position with the switch control relay WZ and the track switch TS while the track switch is locked, but

-this is immaterial to the selection of the signal control circuits as at that time the signal control circuits are actually established and the switch is actually locked, so that any movement of the .free control lever at that time is ineffective to cause any interruption of the signal control circuits then established.

If it is desired that the positioning of the switch control levers, such as lever CL, for example, while thc track switch is locked, be effective to operate the track switch subsequent to the unlocking of the track switch, and so related with the track switch as to prevent the clearing of an erroneous route under such conditions, the association of the lock relay L with the signal control lever (not shown) and the interrelation of the control lever CL with the relay WP, can be accomplished as disclosed, for example, in the pending application of Dicke et al., Ser. No. 640,378, above mentioned.

The present invention provides the features of positive action without the disadvantage of the locking up of the system in the event of a failure oi the track switch operating mechanisms to respond to operations in the mechanical type of interlocking systems to which the present invention has been shown as applied in Fig. 1.

Having described an interlocking system including either a free lever or a mechanical interlocked lever, as specic embodiments of the present invention, it is desired to be understood that these forms are selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specic form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appended claims.

What we claim is:

l. In an interlocking system for railroads, a switch machine for operating a railroad track switch, a control device having normal and reverse positions, a normal contactor, a reverse contactor, a common contactor, point detector contacts controlled jointly by said switch machine and. said track switch, a switch position indicating relay, means for energizing said normal contaeter only when said control device is in a normal position and said switch machine is in a reverse or mid stroke position, means for energizing said reverse contactor only when said control device is in a reverse position and said switch machine is in a normal or mid stroke position, means for energizing said switch position indicating relay in accordance with the position of said track switch as indicated by said point detector con- 5 tacts only when said normal, reverse and common contactors are all deenergized, means for energizing said common contactor only when the particular normal or reverse contactor is energized in accordance with the position of said coni0 trol device and said switch position indicating relay is deenergized, and normal and reverse operating circuits for said switch machine selected by said control means but closed only upon the energization of said common contactor. l5

2. In an interlocking system for railroads, a switch machine for operating a railroad track switch, a normal contactor, a reverse contactor, a common contactor, an indicating relay for indicating the position of said track switch only when said normal, reverse and common contactors are deenergized, means for at times energizing either said normal or said reverse contactor thereby deenergizing said indicating relay, means energizing said common contactor only when one of said 25 normal and reverse contactors is energized and said indicating relay is deenergized, means causing operation of said switch machine to normal or reverse positions in accordance with said normal or reverse contactors respectively only when 30 said common contactor is energized, and traflic controlling circuits selected in accordance with the position of said track switch as indicated by said indicating relay.

3. In combination, a switch machine for operating a railroad track switch to normal and reverse extreme positions, control means capable of assuming normal, reverse and inactive positions, an indicating relay for indicating the normal or reverse positions of the track switch when and only when" said control means assumes an inactive position and at other times indicating an unlocked condition of the track switch, a common controller capable of being rendered active only when said control means is in a normal and reverse position, and said indicating relay indicates an unlocked condition of the track switch, normal or reverse operating circuits for said switch machine selected by said control means in corresponding positions but closed only if said common controller is being rendered active, and other circuits selected by said indicating relay.

4. In combination, a switch machine for operating a railroad track switch to normal and reverse positions, a control lever having normal and reverse positions, normal and reverse contactors at the switch machine, a common contactor at the switch machine, an indicating relay for indicating the normal, reverse or unlocked condition of the track switch when all of said contactors are deenergized and for indicating an unlocked condition when any one or all of said contactors are energized, energizing means for said normal contactor eiective when the track switch is in a reverse or mid stroke position and said lever is in a normal position, energizing means for said reverse contactor effective when the track switch is in normal or mid stroke positions and said lever is in a reverse position, energizing means for said common contactor effective when said lever is in a normal or reverse position and the corresponding normal or reverse contactor is energized with said indicating relay indicating the unlocked condition of the track switch, normal or reverse operating circuits for said switch machine closed when the corresponding normal or reverse contactor is enl ergized only if the common contactor is also energized, and circuits selected by said indicating relay vonly when a normal or reverse position of the track switch is indicated.

5. In combination, a switch machine for operating -a railroad track switch to normal and reverse positions, a control lever having normal and reverse positions, normal and reverse contactors at the switch machine, a common contactor at the switch machine, an indicating relay for indicating the normal, reverse or unlocked condition of the track switch when all of said contactors are deenergized and for indicating an unlocked condition when any one or al1 of said contactors are energized, energizing means for said normal contactor effective when the track switch is in a reverse or mid stroke position and said lever is in a normal position, energizing means for said reverse contactor eiective when the track switch is in normal or mid stroke positions 'and said lever is in a reverse position, energizing means for said common contactor effective when said lever is in a normal or reverse position and the corresponding normal or reverse contacter is energized with said indicating relay indicating the unlocked condition of the track switch, normal or reverse operating circuits for said switch machine closed when the corresponding normal or reverse contactoris energized only if the common contactor is also energized, a slow acting relay energized only when said indicating relay and said lever are out of corresponding normal or reverse positions or said indicating relay indicates the unlocked condition of the track switch, and means energized whenever said lever and said indicating relay assume corresponding positions only while the contacts ofsaid slow acting relay are still picked up.

6. In combination, a track switch, a switch machine for operating the track switch, a relay for distinctively indicating the position and locked condition of said track switch, a control lever for governing the operation of said track switch, an indication latch mechanism governing the operation of said lever, a slow acting relay, energizing means for said slow acting relay effective whenever said indicating relay indicates the switch to be unlocked and whenever said lever is out of its position corresponding to the locked position indicated by said indicating relay, and means for actuating said indication latch mechanismfwhenever said lever and said indicating relay are in corresponding positions only when the contacts of said slow acting relay are still picked up.

7. In combination; a track switch; a switch machine for operating said track switch; a control lever having normal and reverse fulll positions, and normal and reverse indication positions; an indication latch mechanism allowing the movement of said lever to a full position from the corresponding indication position only when released; a relay indicating the position and locked condition of said track switch and its correspondence with said control lever; means energizing said switch machine in accordance with the position of said lever only when said relay indicates a lack of correspondence between said lever and said track switch; and means for releasing said indication latch mechanism whenever said lever is in an indicating position corresponding to the position and locked condition of said track switch as indicated by said relay.

8. Incombination; a switch machine for operating a railroad track switch to normal and reverse positions; control means local to said switch machine for controlling its operation, said control means being capable of being pre-conditioned for normal or reverse control and capable of being subsequently rendered effective to accomplish a control operation oi said switch machine in accordance with its pre-conditioning;

a control lever remote from said switch machine; an indication relay associated with said lever for indicating the normal and reverse positions of said track switch and its unlocked condition whenever said track switch is actually unlocked or said control means is pre-conditioned for a new operation of said track switch; means for preconditioning said control means for normal or reverse control in accordance with said control lever; means for rendering said control means eiective to accomplish a control operation of said switch machine only when said indication relay indicates the unlocked condition of said track switch; and means for controlling the movement of said control lever by said indication relay.

9. In combination, a track switch, a switch machine for operating said track switch, an ind,- cating relay for distinctively indicating the position and locked condition of said track switch, a control lever for governing the operation of said track switch, an indication latch meclranism Vgoverning the operation of said lever, a slow acting relay, means controlled by said indicating relay either in a position Vfor indicating the associated track switch unlocked or in a position for indicating the associated track switch locked out of correspondence with the associated lever for energizing said slow acting relay, means for actuating said indication latch mechanism whenever said lever and said indicating relay are in corresponding positions only when the contacts of said slow acting relay are picked up, and means controlled by said indicating relay for deer'ergizing said slow acting relay in response to the locking of said track switch in correspondence with said control lever.

10. In combination; a switch machine for operating a railroad track switch to normal and reverse extreme positions; control means capable of assuming normal, reverse and inactive positions; an indicating relay for at times indicating the normal and reverse positions oi said track switch when and only when said control means assumes an inactive position and at other times 5 indicating the unlocked condition of said track switch; a common controller capable of being rendered active only when said control means is in a normal or a reverse position and said indicating relay indicates an unlocked condition ofsaid track switch; normal or reverse operating circuits for said switch machine selected by said control means in corresponding positions but closed only if said common controller is rendered active; and means controlled by said common controller in its inactive position for snubbing said switch machine.

11. In combination; a switch machine for operating a railroadltrack switch to normal and reverse positions; control means local to said switch machine for controlling its operation, said control means capable of being preconditioned for normal and reverse control and capable of being subsequently rendered effective to accomn plish a control operation of said switch machine in accordance with its preconditioning; a control lever remote from said switch machine; an indication relay associated with said lever capable of being energized to one position or another for indicating the normal and reverse positions of said track switch, said indication relay when deenergized indicating the actual unlocked condition of said track switch or the condition that said control means is preconditioned for a new opera- 10 tion of said track switch; means for preconditioning said controlmeans for normal and reverse control in accordancewith the position of said control lever; means for rendering said control means eiective toaccomplish a control operation of said switch machine only when said indication relay is deenergized; and means including said indication relay for controlling the movement of said control lever.

ANDREW LANGDON. GEORGE H. WION. 

